1. Field of the Invention
This invention relates to operating mechanisms as used to releasably maintain movable elements, such as closure elements, in a predetermined position and, more particularly, to an operating mechanism that is actuated through the use of a cable.
2. Background Art
Operating mechanisms incorporating latch systems are used in a multitude of different environments, for both static and dynamic applications. Commonly, the latch system is incorporated into a movable element, such as a closure element, having closed and open states. Through the latch system, the closure element is releasably maintained in the closed position. The latch system is actuatable to change the state thereof, thereby permitting the closure element to be moved from the closed position into the open position therefor.
One form of such an operating mechanism is shown in U.S. Pat. No. 7,198,308, which is commonly owned herewith. The operating mechanism therein utilizes a tubular component that functions both to support the system operating components and provide a graspable length through which the user can reposition the associated closure element.
The tubular component shown in U.S. Pat. No. 7,198,308 has a straight length bounding a passageway within which an operating rod is operatively positioned. The rod translates in a line substantially parallel to the lengthwise central axis of the tubular component, as an incident of which the state of the latch system is changed.
With such a straight, tubular component, it is also feasible to use a flexible cable that is translated to impart operating forces through which the state of the latch system is changed.
In certain applications, the nature of the closure element and the surrounding environment, and/or specific performance requirements may dictate that the elongate “handle” have other than the straight tubular shape depicted in U.S. Pat. No. 7,198,308. Depending upon the diameter of the tubular component, a certain degree of deviation from “straight” for the shape of the tubular component may be permitted while still maintaining the basic configuration of components shown in the above patent. However, at some level of deviation from straight, the system will not be operable using a single, straight rod.
If the use of a rod is desired, transition linkages may be required to transmit operating forces with such a non-straight tubular component. This may not be practical or, even if it is, such a construction may complicate the design and increase attendant costs to the point that such a design is not feasible on a commercial level. Such a design may require the use of multiple, joined, tubular components to produce the desired overall shape of the “handle”. Aside form complicating the design, and potentially increasing its costs, such an arrangement may compromise the structural integrity of the mechanism and, in any event, will eliminate the preferred single piece construction which generally minimizes joints at locations at which moisture and other foreign matter may migrate to within the passageway and potentially degrade components and, in a worst case, interfere with their operation.
Systems incorporating a flexible cable have more flexibility in terms of accommodating non-straight handle shapes and permitting selection of different orientations of the tubular component relative to the latch system. Flexible cables are also desirable from the standpoint that they may avoid rattling, that is common to the use of operating rods, and generally cause less inertial effect in use than do operating rods. Depending upon the degree of deviation of the tubular component from straight, the manufacturer may choose different design options. If the deviation is not significant, the operating components may be integrated substantially the same as they would be with the straight configuration. At some point, the mechanism loses efficiency as forces are applied to and by the cable. That is, if the ends of the cable are skewed from their optimal force application lines, the applied forces to and from the ends of the cable core become only a component of the tension applied to the cable. At some point, the mechanism may be difficult to operate and prone to jamming.
Alternatively, provision must be made to fix the cable sheath so that the cable core length, at each end where connection is made, is properly aligned to exert the maximum operating force on its associated component. Cables are commonly anchored using connectors employing separate fasteners, such as screws or bolts, at each connector location. Aside from the inconvenience of having to stock and manipulate the separate fasteners, these types of fasteners generally allow the orientation of the cable sheath ends to be varied. Thus, even if one were to use such an arrangement, it is possible, depending upon the control of the manufacturing process, either in a facility or in the field, operation of the overall system may vary significantly from one to the next. Thus, aside from the inconvenience associated with manufacture and the potential increase in cost, there is a question of quality control.
The industry continues to seek out practical designs for tubular components that can be configured to provide greater versatility.